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authorMarco Elver <elver@google.com>2021-02-25 17:19:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 09:41:02 -0800
commit35beccf0926d42ee0d56e41979ec8cdf814c4769 (patch)
tree76e12c5cf818b3abcd59d1466c52c518202b0873 /mm/kfence/report.c
parent0825c1d57f02e3fb228bbecad827956d4c796d3a (diff)
kfence: report sensitive information based on no_hash_pointers
We cannot rely on CONFIG_DEBUG_KERNEL to decide if we're running a "debug kernel" where we can safely show potentially sensitive information in the kernel log. Instead, simply rely on the newly introduced "no_hash_pointers" to print unhashed kernel pointers, as well as decide if our reports can include other potentially sensitive information such as registers and corrupted bytes. Link: https://lkml.kernel.org/r/20210223082043.1972742-1-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Cc: Timur Tabi <timur@kernel.org> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kfence/report.c')
-rw-r--r--mm/kfence/report.c18
1 files changed, 10 insertions, 8 deletions
diff --git a/mm/kfence/report.c b/mm/kfence/report.c
index 901bd7ee83d8..4a424de44e2d 100644
--- a/mm/kfence/report.c
+++ b/mm/kfence/report.c
@@ -19,6 +19,8 @@
#include "kfence.h"
+extern bool no_hash_pointers;
+
/* Helper function to either print to a seq_file or to console. */
__printf(2, 3)
static void seq_con_printf(struct seq_file *seq, const char *fmt, ...)
@@ -118,7 +120,7 @@ void kfence_print_object(struct seq_file *seq, const struct kfence_metadata *met
}
seq_con_printf(seq,
- "kfence-#%zd [0x" PTR_FMT "-0x" PTR_FMT
+ "kfence-#%zd [0x%p-0x%p"
", size=%d, cache=%s] allocated by task %d:\n",
meta - kfence_metadata, (void *)start, (void *)(start + size - 1), size,
(cache && cache->name) ? cache->name : "<destroyed>", meta->alloc_track.pid);
@@ -148,7 +150,7 @@ static void print_diff_canary(unsigned long address, size_t bytes_to_show,
for (cur = (const u8 *)address; cur < end; cur++) {
if (*cur == KFENCE_CANARY_PATTERN(cur))
pr_cont(" .");
- else if (IS_ENABLED(CONFIG_DEBUG_KERNEL))
+ else if (no_hash_pointers)
pr_cont(" 0x%02x", *cur);
else /* Do not leak kernel memory in non-debug builds. */
pr_cont(" !");
@@ -201,7 +203,7 @@ void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *r
pr_err("BUG: KFENCE: out-of-bounds %s in %pS\n\n", get_access_type(is_write),
(void *)stack_entries[skipnr]);
- pr_err("Out-of-bounds %s at 0x" PTR_FMT " (%luB %s of kfence-#%zd):\n",
+ pr_err("Out-of-bounds %s at 0x%p (%luB %s of kfence-#%zd):\n",
get_access_type(is_write), (void *)address,
left_of_object ? meta->addr - address : address - meta->addr,
left_of_object ? "left" : "right", object_index);
@@ -210,24 +212,24 @@ void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *r
case KFENCE_ERROR_UAF:
pr_err("BUG: KFENCE: use-after-free %s in %pS\n\n", get_access_type(is_write),
(void *)stack_entries[skipnr]);
- pr_err("Use-after-free %s at 0x" PTR_FMT " (in kfence-#%zd):\n",
+ pr_err("Use-after-free %s at 0x%p (in kfence-#%zd):\n",
get_access_type(is_write), (void *)address, object_index);
break;
case KFENCE_ERROR_CORRUPTION:
pr_err("BUG: KFENCE: memory corruption in %pS\n\n", (void *)stack_entries[skipnr]);
- pr_err("Corrupted memory at 0x" PTR_FMT " ", (void *)address);
+ pr_err("Corrupted memory at 0x%p ", (void *)address);
print_diff_canary(address, 16, meta);
pr_cont(" (in kfence-#%zd):\n", object_index);
break;
case KFENCE_ERROR_INVALID:
pr_err("BUG: KFENCE: invalid %s in %pS\n\n", get_access_type(is_write),
(void *)stack_entries[skipnr]);
- pr_err("Invalid %s at 0x" PTR_FMT ":\n", get_access_type(is_write),
+ pr_err("Invalid %s at 0x%p:\n", get_access_type(is_write),
(void *)address);
break;
case KFENCE_ERROR_INVALID_FREE:
pr_err("BUG: KFENCE: invalid free in %pS\n\n", (void *)stack_entries[skipnr]);
- pr_err("Invalid free of 0x" PTR_FMT " (in kfence-#%zd):\n", (void *)address,
+ pr_err("Invalid free of 0x%p (in kfence-#%zd):\n", (void *)address,
object_index);
break;
}
@@ -242,7 +244,7 @@ void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *r
/* Print report footer. */
pr_err("\n");
- if (IS_ENABLED(CONFIG_DEBUG_KERNEL) && regs)
+ if (no_hash_pointers && regs)
show_regs(regs);
else
dump_stack_print_info(KERN_ERR);